In the course of daily living, humans frequently encounter
situations in which a motor activity, once initiated, becomes
unnecessary or inappropriate. Under such circumstances, the
ability to inhibit motor responses can be of vital importance.
Although the nature of response inhibition has been studied in
psychology for several decades, its neural basis remains
unclear. Using transcranial magnetic stimulation, we found
that temporary deactivation of the pars opercularis in the right
inferior frontal gyrus selectively impairs the ability to stop an
initiated action. Critically, deactivation of the same region did
not affect the ability to execute responses, nor did it inf luence
physiological arousal. These findings confirm and extend
recent reports that the inferior frontal gyrus is vital for
mediating response inhibition.